SECT. xiv. CHEMICAL FUNCTIONS. 419 



hydrogen, chemically united ; but no organic compound 

 contains less than three equivalent atoms, generally a 

 great many more. For example, citric acid, which is 

 lemon juice, contains 12 atoms of carbon, 5 of hydrogen, 

 and 11 of oxygen ; while strychnine contains 44 atoms of 

 carbon, 23 of hydrogen, 4 of oxygen, and 2 of nitrogen. 

 Experiment has proved that the powers which maintain 

 stability among the numerous and complex constituents, 

 of organic substances decrease in energy as the number 

 of the equivalent atoms augments; hence such com- 

 pounds are in less stable equilibrium than those of in- 

 organic bodies, and are more liable to be disturbed and 

 changed into new and more stable forms. 



As the chemical functions are not the same in all the 

 cells, situated as they are in different parts of a plant, 

 they elaborate different substances from the same mate- 

 rials. Besides, new substances are introduced with the 

 growth of the plant, to be acted upon by the light and 

 heat of the different seasons, so that numerous com- 

 pounds may be formed out of a given number of the 

 primary elements. For example, the ultimate elements 

 of wheaten flour, or a grain of ripe wheat, are carbon, 

 the three elementary gases, sulphur, phosphorus, cal- 

 cium, magnesium, and silex ; but during the germina- 

 tion and growth of the plant, its flowering, forming the 

 seed, and ripening the grain, certain portions of these 

 elements chemically combine in definite proportions to 

 form cellulose, starch, sugar, gum, gluten, fibrin, albu- 

 men, casein, and fat, all of which are found in wheaten 

 flour. 



However much plants may differ in their organic pro- 

 ducts, they all agree in producing protein, which takes 

 an active part in the formation of cells ; and all produce 

 neutral hydrates of carbon, such as cellulose, starch, 

 sugar, gum, &c., which consist of carbon, combined 

 with hydrogen and oxygen in the exact proportion that 



B E 2 



